Sealed permanent magnet switch

Abstract

A sealed switch includes C-shaped control and follower magnets disposed along an axis with poles thereof in facing relationship, a set of electrical switch contacts coupled to be selectively opened or closed in dependence upon the position of the follower magnet, and a housing enclosing the set of electrical contacts and the follower magnet, the housing having a nonmagnetic wall extending between the facing poles of the control and follower magnets to provide hermetic isolation of the contacts. In accordance with particularly selected configurations, the control magnet may be mounted for alternatively pushbutton type axial motion or rotational motion within different selected limits and the follower magnet may be mounted for either axial or rotational motion within predetermined limits or both. The magnets may be resiliently biased toward predetermined position limits in some configurations. Regardless of the selected configuration, the contacts remain completely enclosed by the housing to be selectively opened or closed by the follower magnet in response to the positioning of the control magnet.

What is claimed is: 
     
       1. A sealed rotary switch comprising: a control magnet disposed along an axis with coplanar pole faces disposed adjacent one side of a thin nonmagnetic sealing wall, the control magnet being coupled for rotation within a predetermined first angle of rotation at a fixed axial position;   a follower magnet disposed along the axis with coplanar pole faces disposed adjacent a side of a thin, nonmagnetic sealing wall opposite the one side in opposed, facing relationship to the pole faces of the control magnet, the follower magnet being coupled for limited axial motion and for rotation within a predetermined second angle of rotation less than the first angle of rotation with poles of the follower magnet being in aligned opposite polarity attractive relationship to poles of the control magnet when both the control and follower magnets are in midpoints of their respective first and second angles of rotation;   at least one pair of switch contacts;   a conductive-bar resiliently coupled to the follower magnet to selectively close one pair of switch contacts when the follower magnet is at a rotational limit and axially spaced from a nonmagnetic sealing wall;   a coil spring engaging the conductive bar at a midpoint therealong and resiliently coupling the bar to the follower magnet; and   a housing having a control chamber receiving the control magnet and a sealed follower chamber receiving the follower magnet, conductor and switch contacts, the housing having a nonmagnetic sealing wall extending between facing pole faces of the control and follower magnets and separating the control and follower chambers, the switch being operable to move the follower magnet to an axial position proximate the sealing wall when the control magnet is rotated to a rotational angle within the limits of the second angle of rotation, the follower magnet being rotated to a rotational limit as the control magnet rotates to a limit of the second angle and then being repelled to close an associated pair of contacts while remaining rotationally positioned at the limit as the control magnet continues to rotate beyond a limit of the second angle of rotation.   
     
     
       2. The switch according to claim 1 above, further comprising means for preventing the follower magnet from assuming a spaced-apart axial position when the follower magnet is not rotationally positioned at one of the limits of the second angle of rotation. 
     
     
       3. The switch according to claim 1 above, further comprising a resilient element coupled to bias the follower magnet toward a spaced-apart axial position, the bias being insufficient to overcome the attractive forces of the control and follower magnets when they are in substantially aligned opposite pole attractive relationship. 
     
     
       4. The switch according to claim 1 above, wherein the control magnet has a generally cylindrical shape with a circumferentially extending groove of predetermined length defined in the periphery thereof and wherein the control cavity of the housing includes a tab extending into engagement with the groove to limit rotation of the control magnet to a first angle of rotation. 
     
     
       5. The switch according to claim 4 above, wherein the follower magnet has a generally cylindrical shape with an axially extending groove of predetermined circumferential width defined in the periphery thereof, and wherein the sealed follower cavity of the housing includes a tab extending into engagement with the axially extending groove to limit rotation of the follower magnet to the second angle of rotation. 
     
     
       6. The switch according to claim 1 above, wherein both the control and follower magnets both include a C-shaped permanent magnet disposed within a generally cylindrical plastic element. 
     
     
       7. A sealed rotary switch comprising: a control element disposed for rotation about an axis and including a magnet with a plurality of pole faces lying in a plane perpendicular to the axis;   a follower element disposed for rotation about and translation along the axis and including a magnet with pole faces in facing relationship to pole faces of the control element;   means defining rotational and axial translation limits for the follower element;   a conductive bar coupled in fixed rotational relationship to the follower element;   a spring resiliently coupling the conductive bar to the follower element to permit relative axial motion between the conductive bar and follower element;   a set of switch contacts disposed for selective closure by the conductive bar when the follower element is at a rotational limit; and   a housing sealingly enclosing the follower element and set of switch contacts.   
     
     
       8. The sealed rotary switch according to claim 7 above, further comprising a first control element detent for positioning the magnets of the control and follower elements in similar polarity alignment when the follower element is at a counterclockwise rotational limit and a second control element detent for positioning the magnets of the control and follower elements in similar polarity alignment when the follower element is at a clockwise rotational limit. 
     
     
       9. The sealed rotary switch according to claim 8 above, further comprising means for limiting rotation of the follower element to an angle of approximately 90°. 
     
     
       10. The sealed rotary switch according to claim 9 above, further comprising means for rotating the angle of rotation of the control element to no more than approximately 180°. 
     
     
       11. The sealed rotary switch according to claim 7 above, wherein the set of switch contacts includes pairs of switch contacts disposed along a diameter of the follower element at different rotational limits and a conductive bar coupled to the follower element to selectively close a pair of switch contacts when the follower element is positioned at a rotational limit and axially spaced from the control element.